Publications Details

Water injection-induced shear fracturing in the Ekofisk Field

Teufel, Lawrence W.

For several years Phillips Petroleum Company has been waterflooding portions of the Ekofisk Field reservoir for purposes of enhanced oil recovery. Boreholes drilled in waterflooded portions of the reservoir have encountered poor core recoveries and highly fractured rock (poor core recoveries and highly fractured zones were not uncommon in the Ekofisk reservoir before waterflooding, however). Results of laboratory compression tests designed to simulate production-related compaction and subsequent waterflooding indicate that injection pressures currently used to inject seawater into the reservoir are high enough to induce shear failure in high porosity reservoir chalks. A model of chalk deformation explains brittle failure of chalk that has been subjected to stresses well in excess of yield stress.